By referring to high-power class AB amps, I imply that it is almost impossible to preserve good dynamics of such amps with extensive use of LC and RC filtering in PS.

Depends, with LC filtering it is most certainly possible. Common "massive" supplies have around 0.5 Ohm DCR (measure by loading the supply, see how much the PSU Voltage drops), so adding 0.1 Ohm like with Manganese/Ferrite cored chokes is not really cramping the Amp's style too much.

It is also possible to use active circuits in the supply to push the power supply impedance into the tens of milliohms way past up to many 100Khz and that without resorting to tons of looped feedback in the power supplies either. In fact, you may find that the output impedance of the Powersupply can be such that it acts as "expander", reducing it's impedance as more current is drawn (one has to watch this effect, it can easily run away on you)...

Quote:

Originally Posted by VladimirK

But with standard simple C filter, this C and power cord become included in the signal chain, as well as speaker cables. Even the circuit breaker at house switchboard play a role.

The role is not direct. There is a rectifier in between and we apply substantial
averaging to the signal before it hits the mains. But yes, with the right amp and speaker and old wiring in the house it is entirely possible to have the lights dim with every big "paukenschlag", a very graphic illustration of this...

ISTM therefore that an amp which is immune to cables won't get sold through any kind of dealer because its less attractive a financial proposition than one which sounds better when partnered with a $1,000 mains lead. Am I missing something?

You are missing that making amplifiers that are immune to cable effects AND can be legally sold, meaning they have to fulfil certain electrical and other safety requirements (which often mandate things that run counter to the requirements for good sound quality) is while not completely impossible (not much is impossible in this universe) is not a trivial matter (to say the least), unless we use transformer coupling and battery power (which in itself is non-trivial)...

You are missing that making amplifiers that are immune to cable effects AND can be legally sold, meaning they have to fulfil certain electrical and other safety requirements (which often mandate things that run counter to the requirements for good sound quality) is while not completely impossible (not much is impossible in this universe) is not a trivial matter (to say the least), unless we use transformer coupling and battery power (which in itself is non-trivial)...

Nope, I'm fully aware that its not trivial. But where's the incentive to try?

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Dear Vladimir,
Depends, with LC filtering it is most certainly possible. Common "massive" supplies have around 0.5 Ohm DCR (measure by loading the supply, see how much the PSU Voltage drops), so adding 0.1 Ohm like with Manganese/Ferrite cored chokes is not really cramping the Amp's style too much.

I am afraid I disagree with you at this point. So called choke-input power supplies inevitably make amps intended for jazz and vocal, one should forget about punch and drive with rock music. This conclusion is now an axiom among russian audiophiles (equipment users), and from technical point of view, I can not imagine how amp could pump 60A peak current to load during high-level bass notes (maybe many Farads lytics reservoir could help) Active resistance of the choke plays almost no role, but its L affects charging pulses drastically.
Nelson Pass repeated maybe hundred times, that amps are intended for applications. The one best for rock will never be best for jazz.
I am lucky, since any rock is not my kind of music, and I can implement "slow" and high Zout power supplies, but extremly cleaned from any HF noise.

I tried to e-mail you, but it looks like something is broken here: instead of e-mail page I am getting support.diyaudio.com page with unrelated information. Send me e-mail and I introduce you to each other.

Thanks.
Please send me a PM. I tried to email you and got the same support page. Your PM box is full.